Notes: STB 20 Jun 2013
D Bojantchev & RM Davis. 2012. Amanita augusta, a new species from California and the Pacific Northwest. North American Fungi 8(5): 1-11. doi: http://dx.doi: 10.2509/naf2013.008.005
Amanita augusta Bojantchev & R.M. Davis sp. nov. FIGS. 2–7 MycoBank number: MB 801321
Pileo 30–150 mm lato, hemispherico, dein planoconvexo, subglutinoso, brunneo dein flavo, margine non striato, cum velo generali floccis flavo-luteis. Lamellis confertis, liberis, albis. Stipite 40–150 mm longo, cylindrico, velo basali subfloccoso, interdum flavido, basi bulbosis. Annulo supero, reflexo lacero, flavo. Carne albido. Sapore miti. Sporis 8.5–9.3 × 6–6.8 μm, ellipsoideae, hyalinis, amyloideae. Basidiis 35– 62 × 8–12 μm, tetrasporigeris, fibulis absentibus, cellulis marginalis spheropedonculatibus interdum subglobosibus.
TYPE: USA. CALIFORNIA: SONOMA COUNTY, Salt Point State Park, 0.25 mi. South of Hwy 1 (38°33′36′′N 123°18′50′′W), under Notholithocaprus densiflorus, Pinus muricata, Pseudotsuga menziesii, 11 Dec 2011, Bojantchev DBB49390 (Holotype UC 1851352; Genbank nrITS JQ9372).
ETYMOLOGY: In Latin Augustus means majestic or venerable, a name befitting this distinctive Amanita species.
PILEUS 30–150 mm diam., hemispherical to convex when young, plano-convex to plano- concave with age; margin incurved to straight, occasionally ribbed striate near the margin; color dark brown to brown to yellow brown, sometimes yellow to grayish yellow at age, typically paler towards the margin; the universal veil forming rows of concentric warts (finer towards the edge), yellow, but fading to grayish-white with age, easily removable, often partially or completely washed out or rubbed away, leaving the pileus partially or fully glabrous. LAMELLAE crowded, 9– 20 mm broad, white to yellowish near the cap margin, even, narrowly attached to free; lamellulae common. STIPE 40–150 mm long, 10– 30 mm wide, context stuffed, cylindrical to tapering towards the apex, often with a distinct bulb; color yellow when young, often fading to whitish at age, typically yellowish above the annulus; surface above the bulb forming scaly girdles (finer towards the annulus) with yellow apices, often fading to glabrous at age; surface above the annulus distinctly longitudinally striate. ANNULUS superior, membranous, pendant, upper surface distinctly striate, thinning, but rarely collapsing with age, typically fimbriate, pale yellow to yellow on both sides, developing darker yellow brown zones at age. STIPE BASE prominent bulb in most basidiomata, girdled with veil remnants, distinctly rufescent in age. UNIVERSAL VEIL yellow. CONTEXT white to pale yellow. ODOR mild. TASTE mild. SPORE DEPOSIT white.
BASIDIOSPORES (7.8–)8.5–9.3(–11.2) × (5.2–) 6.0–6.8 (–7.8) μm (mean 8.9 × 6.4 μm), Q = 1.27–1.57, Qav = 1.41 (N = 201, 6 basidiomata, 3 collections), broadly ellipsoid to ellipsoid, slightly to distinctly inequilateral in 30–40% of the cases, with a prominent lateral apiculus, hyaline, amyloid. BASIDIA 35–62 × 8–12 μm, 4-spored, clavate; sterigmata 4–6 μm long; no clamps observed. SUBHYMENIAL LAYER composed of several layers of irregular to pyriform cells 9–31 × 7–21 μm, not clamped. LAMELLAR TRAMA divergent, composed of filamentous to swollen hyphae 6–22 μm wide, no clamps observed. LAMELLAR MARGINAL CELLS subglobose to sphaeropedunculate 10–33 × 7–21 μm (Fig. 4a). PILEIPELLIS an ixocutis of densely interwoven hyphae 2–7 μm wide with the upper layer slightly gelatinized. ANNULUS composed of filamentous cells, 2–6 μm wide, on the lower surface with clusters of inflated subglobose to pyriform cells, 10–30 × 8–24 μm (Fig. 4b), with a few inflated cells on the upper surface; clamp-connections not observed. UNIVERSAL VEIL formed of dense filamentous hyphae 2–8 μm wide, interspersed with broadly ellipsoid to subglobose vesiculose cells, 30–80 × 14–60 μm; no clamps observed. STIPE TRAMA acrophysalidic, composed of filamentous hyphae 2–6 μm wide and inflated hyphae 62–176 × 16–44 μm; no clamps observed. OLEIFEROUS HYPHAE abundant, 7–20 μm wide with refractive content (Fig. 4c).
HABITAT AND DISTRIBUTION — Amanita augusta is common in the mixed coastal woods of California, the Pacific Northwest, and Alaska (Fig. 8). Reports of collections from the Sierra- Cascade mountain ranges are scarce, particularly in California. The primary fruiting period is autumnal but basidiomata may be collected in the late summer and fall in the Pacific Northwest and in the winter and spring in California. It tends to fruit in small numbers, typically 1-3 basidiomata, rarely more. Amanita augusta is an ectomycorrhizal species and along the range of its distribution it is found in mixed conifer and broadleaved habitats, amongst a number of potential hosts. The exact associations are not fully mapped out yet, but amongst the established ectomycorrhizal hosts are P. muricata (Bruns et al. 2002) and Ps. menziesii (Smith et al. 2002), while Tsuga heterophylla is listed as probable (Trappe 1960). In addition, we have observed A. augusta in solid stands of live oak (Quercus agrifolia) in California and Sitka spruce (Picea sitchensis) in Alaska, as well as in mixed conifer spruce (Pi. engelmannii) in Oregon. Tanoak (N. densiflorus) is a common tree in much of its distribution in California. Future research will undoubtedly shed more light on the exact associations from the number of other potential conifer and broadleaved hosts.